This application claims the benefit of Korean Application No. 99-56558, filed Dec. 10, 1999, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method of driving a plasma display panel, and more particularly, to a method of driving a three-electrode surface-discharge plasma display panel.
2. Description of the Related Art
FIG. 1 shows a structure of a general three-electrode surface-discharge plasma display panel, FIG. 2 shows an electrode line pattern of the panel shown in FIG. 1, and FIG. 3 shows an example of a pixel of the panel shown in FIG. 1. Referring to the drawings, address electrode lines A1, A2, . . . Am, dielectric layers 11 and 15, Y electrode lines Y1, . Y2, . . . Yn, X electrode lines X1, X2, . . . Xn, phosphors 16, partition walls 17 and an MgO protective film 12 are provided between front and rear glass substrates 10 and 13 of a general surface-discharge plasma display panel 1.
The address electrode lines A1, A2, . . . Am are provided over the front surface of the rear glass substrate 13 in a predetermined pattern. The lower dielectric layer 15 covers the entire front surface of the address electrode lines A1, A2, . . . Am. The partition walls 17 are formed on the front surface of the lower dielectric layer 15 to be parallel to the address electrode lines A1, A2, . . . Am. The partition walls 17 define discharge areas of the respective pixels and prevent optical crosstalk among pixels. The phosphors 16 are coated between partition walls 17.
The X electrode lines X1, X2, . . . Xn and the Y electrode lines Y1, Y2, . . . Yn are arranged on the rear surface of the front glass substrate 10 so as to be orthogonal to the address electrode lines A1, A2, . . . Am, in a predetermined pattern. The respective intersections define corresponding pixels. Each of the X electrode lines X1, X2, . . . Xn and the Y electrode lines Y1, . Y2 . . . Yn comprises a transparent, conductive indium tin oxide (ITO) electrode line (Xna or Yna of FIG. 3) and a metal bus electrode line (Xnb or Ynb of FIG. 3). The upper dielectric layer 11 is entirely coated over the rear surfaces of the X electrode lines X1, X2, . . . Xn and the Y electrode lines Y1, . Y2, . . . Yn. The MgO protective film 12 for protecting the plasma display panel 1 against strong electrical fields is entirely coated over the rear surface of the upper dielectric layer 11. A gas for forming plasma is hermetically sealed in a discharge space 14.
The above-described plasma display panel 1 is basically driven such that a reset step, an address step and a sustain-discharge step are sequentially performed in a unit subfield. In the reset step, wall charges remaining from the previous subfield are erased and space charges are evenly formed. In the address step, the wall charges are formed in a selected pixel area. Also, in the sustain-discharge step, light is produced at the pixel at which the wall charges are formed in the address step. In other words, if alternating pulses of a relatively high voltage are applied between the X electrode lines X1, X2, . . . Xn and the corresponding Y electrode lines Y1, Y2, . . . Yn, a surface discharge occurs at the pixels at which the wall charges are formed. Here, plasma is formed at the gas layer of the discharge space 14 and phosphors 16 are excited by ultraviolet rays to thus emit light.
FIG. 4 shows the structure of a unit display period based on a driving method of a general plasma display panel. Here, a unit display period represents a frame in the case of a progressive scanning method, and a field in the case of an interlaced scanning method. The driving method shown in FIG. 4 is generally referred to as a multiple address overlapping display driving method. According to this driving method, pulses for a display discharge are consistently applied to all X electrode lines (X1, X2, . . . Xn of FIG. 1) and all Y electrode lines (Y1, Y2, . . . Y480) and pulses for resetting or addressing are applied between the respective pulses for a display discharge. In other words, the reset and address steps are sequentially performed with respect to individual Y electrode lines or groups, within a unit sub-field, and then the display discharge step is performed for the remaining time period. Thus, compared to an address-display separation driving method, the multiple address overlapping display driving method has an enhanced displayed luminance. Here, the address-display separation driving method refers to a method in which within a unit subfield, reset and address steps are performed for all Y electrode lines Y1, Y2, . . . Y480, during a certain period and a display discharge step is then performed.
Referring to FIG. 4, a unit frame is divided into 8 subfields SF1, SF2, . . . SF8 for achieving a time-divisional gray scale display. In each subfield, reset, address and display discharge steps are performed, and the time allocated to each subfield is determined by a display discharge time. For example, in the case of displaying 256 scales by 8-bit video data in the unit of frames, if a unit frame (generally {fraction (1/60)} second) comprises 256 unit times, the first subfield SF1, driven by the least significant bit (LSB) video data, has 1 (20) unit time, the second subfield SF2 2 (21) unit times, the third subfield SF3 4 (22) unit times, the fourth subfield SF4 8 (23) unit times, the fifth subfield SF5 16 (24) unit times, the sixth subfield SF6 32 (25) unit times, the seventh subfield SF7 64 (26) unit times, and the eighth subfield SF8, driven by the most significant bit (MSB) video data, 128 (26) unit times. In other words, since the sum of unit times allocated to the respective subfields is 257 unit times, 255 scales can be displayed, 256 scales including one scale which is not display-discharged at any subfield.
In the driving method of the multiple address overlapping display, a plurality of subfields SF1, SF2, . . . SF8 are alternately allocated in a unit frame. Thus, the time for a unit subfield equals the time for a unit frame. Also, the elapsed time of all unit subfields SF1, SF2, . . . SF8 is equal to the time for a unit frame. The respective subfields overlap on the basis of the driven Y electrode lines Y1, Y2, . . . Y480, to form a unit frame. Thus, since all subfields SF1, SF2, . . . SF8 exist in every timing, time slots for addressing depending on the number of subfields are set between pulses for display discharging, for the purpose of performing the respective address steps.
FIG. 5 shows an electrode line pattern of the general plasma display panel 1 driven based on the address-display separation driving method. Referring to FIG. 5, in the general plasma display panel based on the address-display separation driving method, each of the address electrode lines A1, A2, . . . Am is cut in a middle portion to form an upper panel and a lower panel. A first Y electrode line Y1 to an   n  2
th Y electrode line   Y      n    2  
and a first X electrode line X1 to an   n  2
th X electrode line   X      n    2  
are allocated to the upper panel. An   (            n      2        +    1    )
th Y electrode line to an nth Y electrode line Y1 and a   (            n      2        +    1    )
th X electrode line   X            n      2        +    1  
to an nth X electrode line Xn are allocated to the lower panel. As described above, since the plasma display panel 1 is separated into two parts to then be simultaneously driven, an addressing time is reduced to a half.
In order to drive the separately driven plasma display panel shown in FIG. 5 by the address-display overlapping driving method shown in FIG. 4, a driving method in which the minimum driving period consisting of a minimum display discharge period, a minimum reset period, and a minimum address period is consistently repeated, is generally used. According to this driving method, the pulses for display discharges are alternately applied to all Y and X electrode lines during the minimum display discharge period, and the minimum reset and address periods are applied between the minimum display discharge periods. In other words, the minimum reset and address periods are applied during the quiescent period of a sustained discharge. Here, during the minimum address period, the scan pulses are applied to at least one Y electrode line in the order of the respective subfields SF1, SF2, . . . SF8, and the corresponding display data signals are applied to the respective address electrode lines.
When the above-described driving method is adopted to the separately driven plasma display panel, the phase of the minimum driving period of the upper panel has been conventionally equal to that of the lower panel. Accordingly, since the upper and lower panels have the driving period of the same mode at the time, the overall maximum instantaneous power becomes increased. For example, if all display cells of the upper and lower panel emit light during the minimum display discharge period, the overall instantaneous power is considerably increased. Due to the considerable increase in the maximum instantaneous power, the burden in the capacity of a power supply circuit and the effects of noise and electromagnetic interference are also increased.
To solve the above problem, it is an object of the present invention to provide a method of driving a plasma display panel which can reduce the burden on the capacity of a power supply circuit and the effects of noise and electromagnetic interference.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and other objects of the invention, there is provided a method of driving a plasma display panel having address lines cut into two parts to form first and second panels which are separately driven, the method comprising generating driving periods of different modes at any given time for the first and second panels.
To achieve the above and other objects of the invention, there is also provided a method of driving a plasma display panel having address lines cut into two parts to form first and second panels which are separately driven, the method comprising temporally alternating minimum display discharge periods for each of the first and second panels.
To achieve the above and other objects of the invention, there is still also provided a method of driving a plasma display panel having front and rear substrates opposed to and facing each other, X and Y electrode lines formed between the front and rear substrates to be parallel to each other, address electrode lines formed to be orthogonal to the X and Y electrode lines, to define corresponding pixels at interconnections, and the address electrode lines are cut into two parts at the middle portions thereof to then form first and second panels separately driven such that the minimum driving period includes a display discharge period, a reset period and an address period, a scan pulse is applied to at least one of the respective Y electrode lines during the address period and the corresponding display data signals are simultaneously applied to the respective address electrode lines to form wall charges at pixels to be displayed, pulses for a display discharge are alternately applied to the X and Y electrode lines to cause a display discharge at the pixels where the wall charges have been formed, and a reset pulse for forming space charges while erasing the wall charges remaining from the previous subfield is applied to the corresponding Y electrode lines during the reset period, wherein the address period is applied to the second panel while the display discharge period and the reset period is applied to the first panel.
Accordingly, since the upper panel and the lower panel have driving periods of different modes all the time, the maximum instantaneous power is relatively decreased. For example, for all display cells of the upper and lower panels, the minium display discharge periods alternate temporally. Thus, the overall instantaneous power is relatively decreased. Therefore, the burden in the capacity of a power supply circuit and the effects of noise and electromagnetic interference can be reduced.